Portable battery-powered communication devices along with associated accessories are advantageous in many environments, but particularly in public safety environments such as fire rescue, first responder, and mission-critical environments. For example, a battery powered two-way radio may interface to a portable audio accessory, such as a remote speaker microphone (RSM), via a wired cable. In such public safety type environments, the interface used between the portable radio and wired accessory tends to include simple but reliable analog signals and general purpose input/output (GPIO) signals which are difficult to re-use in some cases. Additionally, modern media-intensive devices need higher speed and more flexible interfaces to meet product and user requirements. Since cost and connector size are often concerns, these interface types are in conflict and there is strong motivation to keep connector size small and pin count low. It is highly desirable to take advantage of higher speed interfaces more closely associated with consumer-type architectures. Such an interface is advantageous not only in terms of cost, but also in terms of simplified usage.
While some limited use of consumer universal serial bus (USB) connectivity has been achieved there is still a need to make the interface more robust, particularly for portable public safety type devices. The challenge of such an interface is that it must meet cost, size, and speed requirements while also being able to maintain a level of robustness suitable for mission-critical operation. For example, an audio accessory having (PTT) functionality (from a PTT button) and audio functionality (from a speaker) would need to be minimally impacted by electrostatic discharge (ESD) and contact bounce.
Accordingly, there is a need for method and apparatus providing expanded interface operation between a portable communication device and an accessory.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.